Feeds

Tiny typo blamed for massive IE security fail

That'll teach you to keep your ampersands in order

Protecting against web application threats using SSL

One small typo in Microsoft's code caused the security vulnerability that prompted Microsoft to release an out of sequence patch on Tuesday, it has emerged.

A rogue ampersand ("&") created a security hole in a the MSVidCtl ActiveX control that hackers began exploiting early this month. A blog posting on Microsoft's Security Development Lifecycle (SDL) by Michael Howard, a security program manager at Microsoft, explained that the minor typo corrupted the code used by the ActiveX control. This in turn created a buffer-overflow bug, he explains.

The extra ‘&’ character in the vulnerable code causes the code to write potentially untrusted data, of size cbSize, to the address of the pointer to the array, pbArray, rather than write the data into the array, and the pointer is on the stack. This is a stack-based buffer overrun vulnerability.

Microsoft's Visual Studio development tool uses the same Active Template Library (ATL) code, prompting Microsoft to issue an update for its coding tools at the same time as pushing out an update for IE.

Howard explained that the flaw was of a type that made it difficult to spot during code review. "In the SDL we require that teams fuzz their controls, but our fuzzing tools didn’t find this because the method in question requires a specially formed input stream that includes many sentinel bytes," Howard explained.

Microsoft plans to update its fuzzing tools so that they are better at detecting this kind of error. It will also mandate the use of newer ATL code.

The cause of the vulnerability was originally pinpointed by reverse engineer Thomas Dullien (aka Halvar Flake), chief exec of Zynamics, and security researcher Dennis Elser. A blog posting discussing the issue and its possible ramifications can be found here. As the researchers note, the flaw is particularly troublesome because third-party applications that make use of the buggy ATL library are also rendered vulnerable to attack. ®

Reducing the cost and complexity of web vulnerability management

More from The Register

next story
Early result from Scots indyref vote? NAW, Jimmy - it's a SCAM
Anyone claiming to know before tomorrow is telling porkies
TOR users become FBI's No.1 hacking target after legal power grab
Be afeared, me hearties, these scoundrels be spying our signals
Home Depot: 56 million bank cards pwned by malware in our tills
That's about 50 per cent bigger than the Target tills mega-hack
Hackers pop Brazil newspaper to root home routers
Step One: try default passwords. Step Two: Repeat Step One until success
NORKS ban Wi-Fi and satellite internet at embassies
Crackdown on tardy diplomatic sysadmins providing accidental unfiltered internet access
UK.gov lobs another fistful of change at SME infosec nightmares
Senior Lib Dem in 'trying to be relevant' shocker. It's only taxpayers' money, after all
Critical Adobe Reader and Acrobat patches FINALLY make it out
Eight vulns healed, including XSS and DoS paths
Spies would need SUPER POWERS to tap undersea cables
Why mess with armoured 10kV cables when land-based, and legal, snoop tools are easier?
prev story

Whitepapers

Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Beginner's guide to SSL certificates
De-mystify the technology involved and give you the information you need to make the best decision when considering your online security options.